Recently, following the widespread use of portable telephone apparatuses using radio, improvement of their operability has been required. Conventionally, this kind of portable telephone apparatus, when receiving an incoming call from a radio base station, shifts to a conversation state in response to a predetermined specific operation by an operation of the portable telephone apparatus.
The conventional portable telephone apparatus using the radio has a problem that a line is often broken during the conversation depending on its radio communication state. For example, the communication is broken in various cases such as a case where a radio wave from a radio base station becomes weak, a case where a radio wave state becomes poor during movement of the apparatus, and a case where radio wave is weak near a boundary of the area controlled by the radio base station even during non-movement. When a signal comes again from another end of the line, the operator of the portable telephone apparatus must perform the predetermined specific operation again.